Decolorization of methylene blue and methyl orange with Ag doped TiO2 under UV-A and UV-Visible conditions: Process optimization by response surface method and toxicity evaluation

Abstract

MB decolarization with pure TiO2 and Ag doped TiO2 based photocatalytic system were investigated under UV-A and UV-Visible conditions. Different ratios of Ag were used as metal dopant. 1% Ag-TiO2 increased the decolorization efficiencies of MB and MO dyes, also the k(app) constant enhanced under UVA and UV-Visible conditions. A central composite analysis showed the effect of initial dye concentration, pH, Ag-TiO2 concentration and the reaction time of photocatalytic process under UVA irridation in both dyes. The photocatalytic degradation pathways of both dyes by Ag doped TiO2 catalyst were obtained in this study. According to these results, the application of Ag-TiO2 catalyst are proved to be more effective than pure TiO2 catalyst for both MB and MO removal. The toxicity test of Daphnia Magna shows that non toxic wastewater discharge to the receiving environment could be possible with photocatalytic degration by Ag-TiO2 catalyst.